Emulation and hardware virtualization software of various descriptions, most of them obsolete by now:

Category Date Link Notes
Gaming May’11 Dolphin An amazing Wii and GameCube emulator
Apr’11 Emulaunch A multi-emulator front-end suitable for use on a TV
Apr’10 Open Emu A modular emulator that can be used as a Quartz Composer plug-in
Sixtyforce A N64 emulator with the ability to render games in high resolution.
mupen64plus a less polished but cross-platform alternative
DOSBox A special-purpose x86 emulator geared for gaming. See Boxer for an excellent Mac port.
Dec’08 Boycott Advance GBA emulator. Universal binary.
KiGB Gameboy/Gameboy colour emulator.
Sinclair Dec’10 Fuse A recent port of the cross-platform ZX Spectrum emulator Fuse
zxsp Emulates a range of Z80-based devices, including the ZX81 I started out with.
Amiga Dec’10 PUAE Probably the most recent one.
Older E-UAE Cross-platform Amiga emulator that can be used with HiToro, a configuration front-end.
MaxUAE Somewhat dead, with only Power PC binaries available.
Generic x86 Older Virtual PC Used to be the best option for running Windows on Power PC
QEMU See also Q for a Power PC front-end